Today a wide variety of electronic devices are commercially available that are powered by power cells commonly referred to as batteries. Many such power cells are rechargeable electrochemical cells also referred to as rechargeable batteries. Electronic devices that include such rechargeable electrochemical cells can be referred to as rechargeable electronic devices. Examples of rechargeable electronic devices include modern mobile communication devices, such as computers, cellular telephones portable/mobile radios, personal digital assistants, video terminals, portable/mobile computers with wireless modems, and other wireless communication devices. For purposes of the following discussions, a wireless communication device may also referred to in the art as a subscriber device, a mobile station, mobile equipment, a handset, a mobile subscriber, user equipment, or an equivalent used in any wireless communication standard.
A wired charger device can be used to recharge the power cells in such devices. For example, cellular phones and other wireless communication devices have traditionally been charged via a wired charger device that includes a plug-in cord. The wired charger device connects to a power jack socket on the rechargeable electronic device. The power jack socket is wired to contacts with the terminals of the rechargeable electrochemical cells. The wired charger itself usually consists of a plug box containing a step-down transformer and an AC-DC converter or rectifier which is wired via a charging cable to a connecting plug. When in use, the plug box is plugged into an electrical outlet (a 120 V or securing block 240 V mains socket) or a USB port if the charger is USB compatible. The connecting plug is coupled to the rechargeable electronic device that is to be charged.
There are numerous drawbacks associated with wired charger devices. Wired charger devices are bulky items to carry around, and the wire trailing between the device and the plug box can be unsightly. Therefore most users of compact portable equipment such as cell phones and the like do not carry wired chargers with them. Moreover, if the trailing wire is snagged or jerked, the wire; the connectors; the socket; or the wall may be damaged. Furthermore, the rechargeable electronic device may be pulled to the ground. In addition, because not all manufacturers use the same type of wired charger, if a user forget or looses their cable it's not always easy to find a replacement. These are just a few examples of some of the drawbacks or problems that are regularly associated with such “wired chargers.”
Recently, inductive battery charger systems have been developed such as the system described in U.S. Pat. No. 7,164,255 to Hui, which is incorporated herein by reference in its entirety. In Hui's system a planar inductive battery charging system is designed to enable electronic devices to be recharged without wires, and can therefore be referred to as a wireless battery charging system. The system includes a planar charging module. The planar charging module has a charging surface or mat, and parallel to the charging surface is at least one primary coil or winding, and in some cases an array of primary coils or windings. The planar charging module can be plugged into an electrical power source (e.g., a standard outlet, or a USB port). An electronic device to be recharged is placed on the charging surface, and the primary coil(s) can then inductively couple energy to a secondary coil of the device to be recharged. In some conventional electronic devices that do not include secondary coils when manufactured, a separate module (sometimes referred to a receiver) can be coupled to the conventional electronic device to allow it to work with the wireless charger. The receiver has secondary coil(s) that allow the device to be charged via magnetic induction.